This proposal is a competitive renewal of grant CA27489 project 11 and focuses on the development and use of catalytic antibodies. Antibodies that use a reactive amine and an enamine intermediate in their mechanisms are the central focus of this study. The primary activities of these antibodies is catalysis of the aldol reaction, a reaction central to metabolism and the practice of synthetic organic chemistry. This work capitalizes on our development of reactive immunization strategies for this reaction. Haptens will be synthesized for the preparation of antibodies with aldose as well as Diels-Alderase activity. W3e will study schemes that allow for the specific introduction of co-factors into these antibodies in an attempt to further extend their scope. The catalysts that result will be subject to in vitro and in vivo selections using compounds that allow for selection based on catalytic activity rather than binding. The development of novel methods and strategies for the selection based on catalytic activity are essential for continued progress in the area of de novo catalyst preparation. The medical application of these antibodies is based on our encouraging results in the area of pro-drug design and activation. We will explore the potential for targeting catalytic antibodies to tumor sites for the selective activation of pro-drugs in animal models of cancer. Structural studies of antibodies in complex with inhibitors and substrates will provide insight into catalytic mechanism and will aid in the assessment of our ability to program reaction mechanism (with Projects 9 an 10). Cumulatively, these studies will provide a more thorough understanding of enzymes, their evolution, and means for their creation. T catalysts that result should find application in asymmetric organic synthesis and become key tools in selective chemotherapeutic strategies.